Lithornis

Lithornis is a genus of extinct paleognathous birds. Although Lithornis was able to fly well, their closest relatives are the extant tinamous (which are poor flyers) and ratites (which are flightless birds).

Fossils of Lithornis are known with certainty from the Upper Paleocene through the Middle Eocene, but their fossil record may extend to the late Cretaceous. Lithornis is from ancient Greek for 'stone bird', as it is one of the first fossil birds to become widely discussed. Presumably closely related genera are Paracathartes and Pseudocrypturus.